The present invention relaters to an apparatus for hydroforming workpieces and comprises a forming tool with at least a first tool part and at least a second tool part, a press device for closing and holding together the tool parts during a forming cycle, and means for supplying a pressurised fluid to the tool during the forming cycle.
The present invention also relates to a method of hydroforming workpieces and comprises the steps that at least one workpiece is placed in a tool which is closed, whereafter forming takes place and the formed workpiece is removed from the tool
In this application, the term hydroforming is taken to signify a forming method in which a workpiece of sheeting or tubing is directly subjected to a liquid under high pressure in order, under the action thereof, to be formed in or against a tool. The fluid may, in this context, be water, a water/oil emulsion, oil, etc. Hydroforming can achieve extremely high levels of accuracy and surface fineness in the processes workpiece.
WO 95/31322 discloses an apparatus for hydroforming. This apparatus consists of an outer frame in which there are disposed press devices displaying short stroke length, but with extremely high pressing force. A tool unit is divided into a plurality of components and provided with a workpiece outside the press device and is also assembled outside the press device. After assembly of the tool and the workpiece, the tool is inserted as a unit into the press device where it is dosed and held together at the same time as the hydroforming operation takes place in the tool. After completed forming, the tool is removed as a unit and emptied outside the press device. Thus, the press device serves the function of a separate tool locking means.
While the design and construction according to the above-mentioned PCT publication may, in certain cases, function satisfactorily, it is, however, in many situations impractical and slow in operation. This applies particularly to such situations where workpieces of relatively simple shape are to be produced.
Problem Structure
The present invention has for its object to design the apparatus intimated by way of introduction such that it makes for extremely rational production at low costs. The same applies also to the method intimated by way of introduction. A further object of the present invention is to make it possible also to manufacture workpieces of different shapes in rapid sequence after each other.
Solution
The objects forming the basis of the present invention will be attained in respect of the apparatus if this is characterized in that the first tool part is mounted in the press device, while the second tool part is disposed for insertion in the press device prior to a forming cycle, and for removal from the press device after the forming cycle.
The objects forming the basis of the present invention will be attained in respect of the method if this is characterized in that a first tool part is held fixedly and immovably during a work cycle, that at least a second tool part is provided with a workpiece, that the second tool part with the workpiece is brought to a position in connection with the fist tool part and that the tool is closed by displacement of the second tool part and the workpiece, whereafter the forming takes place.
Further advantages will be attained if the apparatus is also given one or more of the characterizing features as set forth in appended subclaims 2 to 5 and if the method is also given one or more of the characterizing features as set forth in appended subclaims 7 and 8.